SparkFun Forums

[BacaBej]

Hello,
i have the same problem like this guy: https://forum.sparkfun.com/viewtopic.ph ... ow#p186975

After uploading a sketch, it runs fine. But when I disconnect the Pro Micro and plug it in, it is like 5 times slower.
I have the 5V version and 5V is selected in the Arduino IDE.

Even if something is broken, why is it at correct speed after uploading ?
In another Thread, someone burnt a new Bootloader to the pro micro with an arduino board. But i just have this pro micro and so its impossible to burn a new Bootloader ?

[Ross Robotics]

What is slow about it?

[BacaBej]

the blinky sketch: https://learn.sparkfun.com/tutorials/pr ... 1-blinkies
is slower (normally its blinking every 1 second, after plugging in, without uploading, its like 5 seconds)

[MattSplatt]

Did anyone find out more about this? I have a couple of Pro Micros here. Both exhibit this same behaviour. When powered up, they run at about 1/8 speed until reset either by uploading a sketch or pushing the reset button.

If I hold the reset pin low while turning them on, even for only a fraction of a second, it subsequently runs at full speed. Maybe the workaround would be an external circuit to do that for a small timeout after powering on. I'll have to figure out how to design such a thing.

Any thoughts?

Is it worth trying a firmware/bootloader update?
I don't have the tools for this at present, but it wouldn't hurt to acquire them and learn how to do it if I'm going to make good use of these fantastic little devices.

[MattSplatt]

I have a workaround.

I'm a newbie at this stuff, but I learned a bit about resistor/capacitor circuits today. I was shooting for a simple 555 timer delay, but I tried this first and it worked:

On the Pro Micro, I put a 0.1uF capacitor between the reset pin and ground, and a 10k resistor between the reset pin and VCC. This holds the reset pin low very briefly after the power comes on, then it resets and runs as it should, at full speed.

This is a 5V/16MHz Pro Micro.

[skimask]

On the Pro Micro, I put a 0.1uF capacitor between the reset pin and ground, and a 10k resistor between the reset pin and VCC. This holds the reset pin low very briefly after the power comes on, then it resets and runs as it should, at full speed.

Pretty much standard practice across the board to delay the RESET line as you describe since way back when...
Why doesn't the Pro Micro do this?
No idea...